ELISA Optimization

I was using a 96 well flexible roundbottom plate and getting very high positive readings of around 3 (abs). I switched to flat bottom, high-binding strip plates and now my absorbance for my positives has dropped to around 2.

It is very normal, different materials plates have different bingding capacity, so have different OD. If you want have stabilized results,maybe you should use the same material's plate in your experience always.